They should have constructed a new signature bridge in China or somewhere cheap with plenty of slave labor, shipped it to Boston in pieces, bring to the Charles on barges, and set it up. This falling apart tourist attraction could then have been demolished at the last minute. $ saved, and years or reconstruction would have been reduced to months.

I may sit corrected - I thought the weekend busing was going both ways on the bridge but it may be true that Cambridge bound buses may have to follow the same detour as everyone else. I just knew that there had to be two way traffic for emergency vehichles and such during the weekend diversions. For some reason, I thought that meant that the buses would be using both lanes.

The intent was to show where things are in relation to the work being performed - Cars, bikes, buses, trains etc. - there is an updated video not online that corrected most of the minor issues like train direction, colors and shadows

Anon - The trains will shift based on the phase and run on temporary 'shoofly' tracks placed on the road deck. I forget what the video shows at each moment but basically there will be a train temporarily on one side of the bridge, then the other - allowing for service to continue except for the aforementioned weekend diversions. You can imagine that some of those weekends are to shift the trains over to their new alignment.

But I didn't understand how or why a train would run on the left-side track at any stage. That would require crossing over on both ends of the bridge, blocking traffic on the other track in the process.

It's not clear to me why the cupolas are being removed at all. They end up in the same place when it's done, and they are not support structures anyhow, just decorative enclosures for the access stairways. Can somebody explain ?

Currently all of the towers have settled in one direction or another. Dismantling the towers will both help fix that situation as well as allow for structural repairs to happen underneath the towers in the piers below. Add to that the fact the towers go back with seismic reinforcement (they're currently just resting on themselves) and those are some if the reasons to dismantle and reassemble. (Plus, it's going to be crazy cool - to me- to see them dismantled piece by piece and then reassembled.) Leaving them in place was going to make all of that other work more difficult and would not have represented any real savings. Why not take the opportunity to do it properly with a clean slate, right?

Way more complicated than the Mass Ave or BU bridges, but way more costly -- $253 million vs $19 million for the BU Bridge project and $16.3 million for the Harvard Bridge re-decking that completed in 1990.

It's the area near the MBTA that no construction equipment can go into as a way to protect the trains while running from any possible accidents. I guess "No-Go" could have been used as well. That's why the excavator has a telescoping arm instead of a bucket. Also why there is a gantry crane instead of a crane with a tall boom.

The weekend shutdowns are for work to the tracks or in that No-Fly space